In using a typical adjustable wrench, the jaws of the wrench are placed around a nut, bolt or the like which is to be loosened or tightened, and a knurled worm gear on the wrench is rotated until the jaws grip the bolt tightly. Because the item being gripped is not normally compressible, it is difficult to tighten the worm gear enough with the fingers to get the jaws of the wrench tight enough against the item so that play in the wrench is eliminated. The play in the jaws of the wrench is undesirable as it increases the likelihood of the jaws slipping on the corners of a nut, for example, thereby deformably rounding the corners and ruining the nut.
There is an adjustable wrench on the market, which is sold by Sears Roebuck & Co., which uses a spring tensioned worm gear to apply bias against the worm gear of the wrench in a direction away from the fixed jaw of the wrench. The spring biased worm of the Sears wrench reduces the amount of play in the worm gear, but does not substantially reduce the amount of play in the jaws as they are tightened around an item, nor does it ensure improved holding power of the jaws about an item. This is because in tightening the jaws around the item, the user is not working to compress the spring but is working, in effect, to compress the item between the jaws, in the same manner as do adjustable wrenches which do not have spring biased worm gears.
Other prior art wrenches in which a spring bias is found are disclosed in U.S. Pat. Nos. 1,778,748 to Bayrer; 753,862 to Eliel et al.; 957,726 to Armstrong; and 3,983,768 to Smith, and in British Pat. No. 207,901 (1922) to Dorvak. None of such prior art noted hereinbefore teaches or suggests the wrench of the present invention.